With 66 million doses of H1N1 vaccine now available in the U.S., municipalities have begun easing restrictions to access, and federal officials believe the vaccine may soon be available to all.

Starting Tuesday, the Tennessee counties of Memphis and Shelby will begin administering H1N1 vaccine to everyone who wants it, joining several other municipalities across the country that have already opened access or are considering doing so.

“I get the sense that more areas are starting to vaccinate outside the priority groups,” said Tom Skinner, a spokesman for the U.S. Centers for Disease Control and Prevention.

Skinner said federal officials have been clear in their desire to have priority groups, such as pregnant women and children, vaccinated first.

"But federal guidelines also give states the flexibility to vaccinate outside the priority groups if the states feel that’s the best thing to do given the issues surrounding supply and demand at the local level," Skinner said.

States are in the best position to make the call to open the vaccine to everyone, Skinner said, adding that more states will be vaccinating outside the priority groups in the coming weeks and months as more of it becomes available.

“There will come a time when everyone will have access to it,” he said.

The H1N1 vaccine became available in the U.S. in early October, about a month after schools and colleges opened. By mid-month, 14 million doses of the vaccine were available, about half of what the U.S. expected to have received from manufacturers.

A top Dallas County (Texas) health official on Saturday called for distribution of the H1N1 vaccine to everyone, as more vaccine appears to be headed toward North Texas pharmacies.

The move comes as interest in obtaining the shot by high-risk groups appears to be waning.

Zachary Thompson, director of Dallas County Health and Human Services, told the Dallas Morning News he was concerned that the vaccine supply already shared with local pharmacies had not found enough takers among the targeted high-risk groups.

A spot check of local pharmacies by The Dallas Morning News last week found that some stores still had hundreds of shots available for people in high-risk groups.

In addition to local pharmacies, chain drugstores including Walgreens and CVS are offering the vaccines in Dallas County.

Walgreens, which is distributing vaccine in 25-30 states, is complying with federal guidelines and immunizing only high-risk groups against the virus, said spokesman Jim Cohn. He said the company would be willing to offer the vaccinations to everyone if that were the directive of the municipal health department.

“We work on a state-by-state and county-by-county basis,” he said. “In some cases, we’re sitting and waiting for the vaccine. In other cases, the (municipal) government came to us early on and asked us to be part of the supply chain so that the vaccine could be distributed as efficiently as possible. We would like to be able to receive and offer vaccine in all 50 states and it is becoming more widely available as time goes on.”

Despite reports of an H1N1 virus mutation in Norway, a federal health official said Tuesday that the H1N1 vaccine is well-matched and still a person’s best defense against the virus.

“We have not seen clusters of resistance,” said Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention. “The cases reported are interesting, but they are not of concern.”

Frieden said the H1N1 virus is gradually decreasing in the United States, but is still widespread in 32 states and people should remain vigilant.

"Although the flu is going down," Frieden said, "it’s far from gone. … And flu season lasts until May so there’s still a lot of time to see what will happen."

The CDC polled 12 health experts who were split as to whether the country will see another surge of H1N1 this flu season.

"One (expert) said flip a coin," Frieden said. "We don’t know what the future will hold. ... What we do know is that the vaccine is the very best way to protect yourself."

To find a Walgreens that offers the vaccine, click here. To find a CVS store that offers the vaccine, click here.

Jessica Doyle contributed to this story.